Selection of Suitable Sowing Window for Boro Rice in Coastal Regions of Bangladesh

Abstract

Suitable adaptation strategies for dry season boro rice cultivation in coastal regions are important for future food security in Bangladesh. This study assessed the effect of sowing date of dry season boro rice as an adaptation strategy, with a focus on maximum utilization of water. The study was conducted at Dacope, Khulna and Amtali, Barguna during the dry seasons of 2016-17 and 2017-18. The experiment comprised six sowing dates between 15^th October to 30^th December including three varieties BRRI dhan28, BRRI dhan67 and BINA dhan10 in split plot randomized design with three replications. In Dacope and Amtali, salt tolerant varieties BRRI dhan67 and BINA dhan10 produced the highest yield (about 6 t ha^-1) when sown in November. Irrespective of locations, the highest irrigation water productivity (1.08 kg m^-3) and highest total water productivity (0.80 kg m^-3) was found when rice was sown in November. Among the two test locations, the lowest irrigation water was used at Amtali and the highest amount of irrigation was required for Dacope due to comparatively high land and low amount of rainfall. This indicated that boro rice can be grown where the fresh water resources are available during the crop growing season. Early sowing is difficult, because most of the land occupied by T. aman rice and late sowing is facing the problem of soil and water salinity. From the perspectives of growth duration, yield performance, water use and water productivity, the best sowing window for boro rice was found in between 15^th November to 15^th December. The data generated during this experiment can now also be used to set-up the APSIM cropping-systems model for subsequent investigations into long-term system performance variability (risk), and also on how these sowing dates and varieties compare under projected future climate change scenarios at these locations.